1. Field of the Invention
The present invention relates to a transistor manufacturing method that is appropriately used when manufacturing various types of displays such as organic EL devices and liquid crystal display devices, and also to an electrooptical apparatus and electronic apparatus that are provided with a transistor manufactured using this manufacturing method.
Priority is claimed on Japanese Patent Applications No. 2003-85757, filed Mar. 26, 2003 and No. 2003-408858, filed Dec. 8, 2003, the contents of which are incorporated herein by reference.
2. Description of Related Art
Generally, thin film transistors (TFT) are formed by patterning a thin silicon film and then injecting impurities into this film. A thin silicon film used in such thin film transistors, integrated circuits and the like is normally formed on an entire surface of a substrate by a vacuum process such as a CVD method, and then the thin silicon film is patterned by removing unnecessary portions by photolithography.
However, the following problems are inherent in this film formation and patterning. Namely, (1) a large size apparatus is necessary, (2) the utilization efficiency of the base material is poor, (3) the base material is a gas which creates handling difficulties and (4) a large volume of waste material is generated. In particular, if the size of the substrate is increased, then the apparatus to process this substrate also needs to be enlarged in order to contain the substrate, which further raises the cost of the apparatus.
In contrast to this traditional method, as is shown, for example, in Japanese Unexamined Patent Application, First Publication No. 2002-203794, a method has recently been disclosed in which a silicon layer is formed by coating liquid high order silane or a solution thereof on a substrate, and then applying heat or the like to the silane. According to this type of method, because the base material is a liquid, it is easy to handle, and because no large apparatus is required, a silicon layer can be manufactured at low cost.
A patterning method has also been disclosed in Japanese Unexamined Patent Application, First Publication No. 2001-179167 in which high order silane solution is provided in predetermined positions by a droplet discharge method such as an inkjet method. According to this type of method, it is possible to omit the photolithographic step and to also eliminate waste material, thereby achieving further reductions in cost.
However, thin film transistors are composed not only of a silicon layer, but also have a variety of component elements such as electrodes and gate insulator films. Accordingly, although it is possible to manufacture channel layers using the above described process, other layers still require a conventional high-cost, large size apparatus to be used for their formation. Therefore, currently, a true reduction in cost is yet to be achieved.
In particular, because gate insulator films have a marked effect on the properties of a thin film transistor, conventionally, they have been manufactured using a proven process such as a CVD method or a thermal oxidation method. However, the apparatus used in a CVD method is large and expensive, while a thermal oxidation method requires processing a substrate at a temperature of 1000° C. or more. Therefore, the considerable problem exists that elements formed on the substrate in the process prior to the thermal oxidation process must be elements that are able to withstand extreme temperature processing.
The present invention was conceived in view of the above circumstances and it is an object thereof to provide a method for manufacturing a transistor that achieves a real reduction in cost and increases the level of processing freedom by doing away with processing at high temperature, and that enables a channel layer and a gate insulator film to be manufactured simultaneously using a liquid silicon material, and to provide an electrooptical apparatus and an electronic apparatus that are provided with a transistor obtained using this manufacturing method.